Radio receiving apparatus



Feb. 10, 1942. K, EMDE RADIO RECEIVING APPARATUS 2 Sheets-Sheet 1 FiledJune 11, 1941 {M Karil'mde E 7 M Feb. 10, 1942. K. EMDE 2,272,937

RADIO RECEIVING APPARATUS Filed June 11, 1941 2 Sheets-Sheet 2 PatentedFeb. 10, 1942 OFFICE RADIO RECEIVING APPARATUS Kurt Emde, Itasca, Ill.,assignor to Zenith Radio a Corporation, Chicago, Ill.

Application June 11, 1941, Serial No. 397,609

1 Claim.-

This invention relates to radio receiving apparatus and moreparticularly to a radio receiving set including an arrangement of partsadapted to provide improved tone qualities and simplified easy tuning.

One of the principal objects of the invention is to provide a moldedgrill construction which will shield or conceal the parts behind it sothat the need for the usual grill cloth, which is expensive anddiflicult to apply, is eliminated.

Another object of the invention is to provide a grill construction whichwill improve to some extent the acoustic properties of a radio receivingset.

Another object of the invention is to provide a receiving set having anovel grill construction so associated with a loud speaker, indicatorneedle and dial that the set as a whole may be made more compactly.

Another object of the invention is to provide a cabinet for a broadcastreceiving unit, including a chassis carrying a loud speaker, arranged sothat the unit may be bodily inserted into the cabinet.

A further object of the invention is to provide comparatively simpledrive means for simultaneously actuating a tuning condenser and a dialindicator.

Still another object of the invention is to provide a pilot lightmounting means which will enable quick and easy assembly of the pilotlight relative to the dial.

One of the principal features of the invention is a novel grillconstruction including louvers arranged concentric with the axis orcenter of the diaphragm of the loud speaker and with a dial and needleindicator interposed between the grill and the loud speaker, the axis ofrotation of the needle indicator also being substantially concentricwith the axis of the loud speaker. The grill, obviously, may be formedintegral with the cabinet as shown herein, or the grill may be mountedupon the cabinet, or formed-and sold as a separate element for use witha loud speaker unit.

Another feature of the invention resides in a comparatively simplemounting means for a dial indicator needle, the mounting means includinga plate preferably secured to the loud speaker and the chassis.

Other objects and features of the invention will be apparent from thefollowing description taken in conjunction with the drawings in which:

Fig. l is a front elevation of a complete receiving set constructed inaccordance with the principles of the present invention:

Fig. 2 is a view of the set with the major por-' tion of the front ofthe cabinet broken away;

Fig. 3 is an enlarged fragmentary sectional view taken on the line 3--3of Fig. 1 and particularly showing the shape of the grill louvers andthe construction of the supporting means for the indicator needle;

Fig. 4 is an enlarged fragmentary sectional view taken on the line @--4of Fig. 2 and particularly showing the mounting means for the tuningshaft and the drive for the rotor shaft of the tuning condenser; and

Fig. 5 is a perspective view illustrating the details of the structureemployed to enable quick and easy mounting of the pilot lights whichserve as illuminating means for the dial.

Referring now to Figs. 1 and 2, the numeral i generally indicates acabinet for the'receiver which may be made of Bakelite, molded plastic,or any other suitable material. The cabinet I is provided with a handle2 whereby it may be readily carried from place to place. The handle 2 issecured to the cabinet l by suitable screws 3 mounted from the interiorof said cabinet (see Fig. 2)

The broadcast receiving unit is generally indicated by the numeral [4and includes a chassis 5 held in place within the cabinet by suitablescrews 6 extended through the bottom I of said cabinet. Pads 8 dependfrom the bottom I of the cabinet and serve to space the cabinet properfrom the surface of a table or other supporting means.

The front wall 9 of the cabinet I is provided with a circular opening l0through which the shaft ll of a conventional on-and-oif and volumecontrol switch l2 extends (see Fig. 2). A knob I3 is frictionallysecured to the shaft ll to facilitate manipulation of the switch andcontrol of the volume.

The front wall 9 is also provided with a circular opening M (Figs. 1 and4) through which a main drive shaft l5 for actuating a tuning condenserIt extends. A tuning knob I! is frictionally mounted upon one end of thedrive shaft i5. The shaft l5 extends through an opening l8 in a frontportion I 9 of the chassis 5. The end of the shaft I 5 opposite thatcarrying the knob l! is reduced in diameter as indicated at 20, therebyproviding a shoulder at N. The reduced end 20 is received in an opening22 formed in a bracket 23 which is welded or otherwise secured to theinner surface of the chassis portion It. The reduced portion 26 isprovided with a circumferential groove 24 for the reception of aconventional split retaining washer 25. Thus, it will be apparent thatthe shaft I is free to rotate relatively to the chassis portion I! andthe bracket 23 and is maintained in assembled relation with the bracket23 by the shoul-- der 2! and the washer 25.

A vertical main plate 26 is provided with oilset tabs 21 (Fig. 2)secured to the chassis 5 by screws 26. A dial 23 having suitable indicia36 to aid in tuning the receiver is secured to the main plate 26 by aplurality of eyelets 3|. The plate 26 is also provided at each of itsupper corners with a circular opening 32 through which a pilot bulb 33for illuminating the dial 2! extends. The opening 32 has diametricallyopposed slots or notches 34 merging thereinto. The pilot bulb 33 iscarried by a generally U-shaped mounting member 35 (see Figs. 3 and 5),said moimting member having laterally extending prongs 36 adapted to bereceived in the slots 34. The prongs 36 are angularly bent, as bestshown at 31 in Fig. 5, and project beyond the extremities of the legs ofsaid U-shaped member to provide shoulder portions 38. The mountingmember 35 is preferably made of material having some springiness so thatthe sides of said member must be pressed toward each other to permit theprongs 36 to pass into the slots 34. Upon release of pressure upon themember 35, the prongs 36 automatically draw the shoulders 33 into tightengagement with the rear surface of the main plate 26 and thus provide ameans for easily, quickly and securely mounting the pilot bulb 33 uponsaid main plate. As is clearly shown in Figs. 1 and 2, two pilot bulbs33 are employed so that the dial 29 is amply illuminated. The uppercorners of the dial 2!! are removed or cut away, as indicated at 39(Fig. 2) so as not to interfere with the insertion of the pilot bulb 33and prongs 36 into the opening 32 and notches or slots 34.

The main plate 26, in addition to being secured to the chassis 5 throughthe off-set tabs 21 and screws 23, is provided with a circulardepression or recess 40 defined in part by a flange 4| (Figs. 2 and 3),which is secured to a conventional loud speaker 42 by circumferentiallyspaced screws 43. The chassis 5 is set back or recessed at 5 (Figs. 2and 3) to accommodate the lower portion of the loud speaker 42 andenable the parts to be more compactly arranged.

Three radial arms 44 extend inwardly from the flange 4| of the plate 26and each arm is off-set, as indicated at 45. The arms 44 merge with eachother at a central hub portion 46 which is concentric with the center oraxis of the speaker cone or diaphragm 41.

The central hub portion 46, as is best shown in Fig. 3, is provided withan aperture 48 adapted to receive one end of a stud shaft 49, a portionof said stud shaft being riveted over the metal of the hub portion topermanently secured the two together. A sheet metal pulley 50 isrotatably mounted upon the stud shaft 4! and includes a solid hubportion 5|, one end of which is reduced, as indicated at 52, to extendthrough a central opening 53 in the pulley 50 and an opening 54 in oneend of an indicatorneedle 55. The reduced portion of the hub 5| ispeened over the outer surface of the pulley 50 so that the hub 5i pulley56 and indicator needle 55 are permanently assembled together in adesired predetermined relation. The stud shaft 43 is provided with agroove 56 adjacent its outer end for the reception of a conventionalsplit washer 51. The washer 51 is adapted to retain the pulley 65 inasembled relation with the shaft 43. A felt washer 56 extends around thestud shaft 43 between the central boss portion 46 of the main plate 26and the innermost portion of the hub 5| of the pulley II. The feltwasher 54 may be saturated with lubricant, if desired.

The tuning condenser l6 (Figs: 2 and 4) is mounted upon the chassis 5 bysuitable fastening means 6|. This condenser is of conventionalconstruction and includes a rotor shaft 62 connected with rotor blades63. A sheet metal pulley 64 has a bracket 65 secured to the rear sidethereof by spot welding or otherwise. The bracket 65 is provided with anopening 66 to receive the rotor shaft 62 and the pulley 64 is providedwith a similar opening 61. A set screw 63 threadedly mounted in thebracket 65 serves to secure the pulley 64 to the rotor shaft 62 innon-rotatable relation.

The pulley 64 (Fig. 4) is provided with a peripheral flange 63 having agenerally V-shaped groove ll formed therein. The flange 69 is severed orbroken and turned back, as indicated at H and 12, respectively, in Fig.2. The drive shaft I5 is provided with a concave groove 13 intermediateits ends, as is best shown in Fig. 4. This groove is adapted to ineffect serve as a drive pulley of comparatively small diameter. Aflexible cable 14 of textile or other suitable material has at least oneturn thereof wrapped around the drive shaft I5 in the groove 13 so as toprovide suflicient friction to substantially preclude relative slidingmovement of said cable with respect to said shaft when the tuning knob11 is rotated. The cable 14 has eyelets l5 and I6 secured to itsopposite ends. The cable 14 snugly engages with the bottom of theV-shaped groove II of the pulley 64 and is arranged so that the endportion thereof having the eyelet I5 extends over the bent flangeportion H and the end portion having the eyelet 16 extends over the bentflange portion 12. One end of a spring II extends through both eyelets15 and I6 and the opposite end of said spring is hooked around apressed-out tongue I8 projecting from the body of the pulley 64. It willbe apparent from the foregoing, that the spring 16 is arranged so as toprovide continuous tension in the cable 14. With portions of the cable14 extending over the bent portions II and 12, a more or less fixedrelation is established between the cable 14 and pulley 64 so thatrotary movement of the drive shaft l5. by turning of the tuning knob 11,will necessarily result in proportionate rotation of said pulley 64 andthe rotor shaft 62 of the tuning condenser, to effect the desired tuningof the set.

The pulley SI associated with the indicator needle 55 has a peripheralflange I9 provided with a generally V-shaped groove 80. The flange I3 isbroken and bent inwardly, as indicated at ti and 32 (Fig. 2), to provideportions similar to the bent portions II and 12 of the pulley 64. Asecond cable 83, preferably of material similar to that employed in thecable 14, is provided with eyelets 84 and 35 in the opposite endsthereof,

at 88 and 88. A pin 88 is fixed to the pulley 64 opposite thelast-mentioned break in the flange 68. The cable 83 extends through theflange 88 and is wrapped around the pin 88 at least once so that thecable 83 is more or less fixedly secured in relation to the pulley 64.The cable 83 extends through openings 83 (Figs. 2 and 4) in the wall ofthe plate 28 defining the recess 48. Thus, it will be apparent thatwhenever the pulley 64 is rotated, corresponding rotation will beimparted to the pulley 58 to rotate the indicator needle 55 throughsubstantially the same angle that the rotor 63 of the tuning condenserl6 has been turned.

The dial needle 55 is adapted to be rotated through a total angle ofabout 188 and it will be noted that the breaks in the flanges of thepulleys 58 and 64 are arranged so as to permit such movement withouthindrance. Again, the dial 28 is of generous size and the portion I3 ofthe drive shaft l is small so that minute adjustment of the indicatorneedle 55 can be attained to simplify and facilitate the tuningoperation.

The front wall portion 8 of the cabinet I is provided with a grillgenerally indicated by the numeral 8|. The grill 8| comprises ahorizontal diametrical web 82 and two series of arcuate or concentriclouvers 93 and 84, one series being arranged above and the other belowthe horizontal web 82. Thecross-sectional shape of the louvers 83 and 84is best shown in Fig. 3, from which it will be noted that each of thelouvers, in addition to being arcuate, extends on an angle ofapproximately 45 and terminates at its outer edge in a bead X. Thelouvers 83 are interconnected at their inner edge portions by verticallyextending webs 85, and the louvers 84 are simi larly interconnected byweb 86, The louvers 83 extend toward their axis exteriorly of thecabinet i and the louvers 84 extend toward their axis interiorly of saidcabinet.

Although the louvers 83 and 84 are arranged concentrically, and may besaid to be dished in opposite directions, the louvers 84 extend in thesame angular direction as the louvers 83 so that the efiect of thelouvers 83 will be to direct the sound waves from the speaker downwardlyand toward a line passing through the axis of the speaker cone 41,whereas the tendency of the louvers 84 is to deflect the sound waves andspread the same in a direction away from the axis of the cone. In thismanner a better distribution of the sound waves emitted by the loudspeaker 42 is accomplished by deflection thereof downwardly, resultingin a better acoustical reproduction of the program being received.

It will also be apparent from Fig. 3 that the louvers 83 and 84 arearranged so that when the set is in its normal position, the plate 25,loud speaker 42, pulley 58, etc., are hidden from view, therebyeliminating the use of the usual grill cloth for this purpose.

The front of the cabinet I is rovided with a dial opening 81 defined inpart by the outermost of the-louvers 83. The dial opening 87 is arrangedso that the indicia 38 on the dial 28 are visible therethrough. Theindicator needle 55 terminates in a more or less arrowhead-like end 88that extends beyond the outermost louver 83 and cooperates with theindicia 38 to indicate the wave length to which the receiving setistuned. A sheet of transparent material 88, such as Celluloid, extendsacross the dial opening 81 in front of the indicator needle 55 and isdetachably secured in place by means of conventional push-type frictionfastening elements 488. Th transparent sheet 88 is cut away behind thelouvers 83, as indicated at l8l (Fig. 1), so as not From the foregoingdescription, it will be apparent that the receiver set may be placedinto operation by turning the switch and volume control knob l3. It willalso be apparent that the set may be tuned to the desired station byturning the tuning knob ll. Rotation of the knob ll, of course, turnsthe drive shaft l5, which drives the pulley 64 through the cable 14. Thepulley 64 in turn drives the pulley 58 through the cable 83, so that theindicator needle traverses the dial 28. The set may be placed out ofoperation by turning the switch and volume control knob l3 back to itsoriginal position, in the-manner well understood. The dial 0r pilotlights 33 are positioned out of alignment with the dial opening 81(Fig. 1) but furnish sumcient light to completely illuminate the dialand are preferably arranged in the circuit so that they are turned onwhenever the knob l3 turns the switch i2 on.

It will be understood that various modifications and changes may be madein the structure herein disclosed without departing from the spirit ofthe invention or the scope of the ap-- pended claim.

I claim:

A grill for use in front of a radio loudspeaker, comprising: a pluralityof concentric louvers, a web extending diametrically of said louvers sothat a series of louvers is arranged upon opposite sides of said web,the louvers of each of said se-- ries being arranged upon an anglerelative to their axis, the louvers of one series extending angularlytoward said axis on one side of the Brill and the louvers of said otherseries extending angularly toward said axis on the opposite side of saidgrill. I

KURT EMDE.

